STEM AND LEAVES OF PLANTS.

to their distance from the stem. The texture of the stem is firm and strong, according to the size of the plant, and the consequent dangers from winds, to which it is exposed. It is composed of small fibres which run parallel to each other in the perpendicular direction, and adhere so firmly as not to be easily separated. In the centre of the stem is the pith, which is soft and very porous. It is inclosed in a fine thin membrane, and is generally supposed to give birth to an essential organ of fructification, which will afterwards be mentioned. The whole stem is covered with a curious bark, which is com posed of three layers, one over another. The outermost serves for protection; the other two increase the diameter of the Stem.

The LEAVES are attached to the branches of plants by means of foot-stalks, which grow off in different directions, forming two layers of a curious net-work, besides a covering over a sort of skeleton of fibres, of a firmer texture, to which these two layers are attached, the one above, and the other beneath. Through the slender foot-stalk, numerous fine vessels run from the branches, and are extended in all directions over the leaf. It appears, that the beautiful green foliage formed by the leaves, is not for mere ornament, but for use; for if a tree be stripped of its leaves in the spring, it soon dies. The sap of the plant being exposed in the leaves to the action of the

LEAVES-VEGETABLES DECOMPOSE WATER.

atmosphere, a very large proportion of it escapes in perspiration, and the rest is supposed to undergo a change essential to the existence of the plant. If this be true, as many eminent physiologists suppose, then the leaves of plants compose an important chemical laboratory, for preparing their juices for future use, as necessary to the plant as the stomach is to the animal.

Of all the parts of plants, (says Sir H. Davy) leaves are the most refined, the most beautiful in their structure, and appear as the master-work of nature in the vegetable kingdom. The elegance of their tints, the variety of their forms, the delicacy of their organization, and the adaptation of their parts, are all calculated to awaken our curiosity, and excite our admiration.*

All kinds of vegetables, when assisted by the rays of the sun, have the power of decomposing water; during which decomposition, the hydrogen is absorbed, and goes to the formation of oil and rosin in the vegetable; while the oxygen combines with part of the caloric received from the sun, and is given out in the form of oxygen gas; so that this one operation of nature gives nourishment, and provides materials of growth to the vegetable world, and, at the same time, renovates that vital principle in the atmosphere which is necessary for the sup

PROCESS OF VEGETATION.

port of the animal creation. Surely nothing short of consummate wisdom could have conceived any thing so beautiful in design, or so extensively and superlatively useful in effect."

That man must be strangely blind who does not see, in this general structure of vegetables, a remarkable suitableness to the mysterious process of vegetation, which the infinitely wise Creator designed to be conducted by it. Here is a singular adaptation of means to an end, and the end is accomplished by these means. Here is nothing wanting, nothing superfluous. If any essential derangement of organization take place, the plant dies, and the end is defeated.

The process of vegetation carried on in this surprising economy, has hitherto baffled the most acute philosophers. But little is yet known concerning it. The multiplicity of operations continually going on in vegetables at the same time, and the variety of different, and even opposite, substances formed out of the same ingredients, and almost in the same place, astonish and confound us. The order, too, and the skill with which every thing is conducted, are no less astonishing. No two operations clash; there is no discord, no irregularity, no disturbance; every object is gained, and every thing is ready for its intended purpose. This is too wonderful to

f Parkes.

INFLUENCE of the vegETATÍVÈ PRINCIPLE.

escape our observation, and of too much importance not to claim our attention. No person has been able to detect the AGENT, always so busy, and performing such wonders, or to discover him at his work; nor have philosophers been much more fortunate in their attempts to ascertain the instruments which he employs in his operations."

This agent has been called the vegetative principle. The nature of the vegetative principle can only be deduced from the phænomena of vegetation. It evidently follows a fixed plan, and its actions are directed to promote the good of the plant. It has a power over matter, and is capable of directing its attractions and repulsions, in such a manner as to render them the instruments of the formation, improvement, and preservation of the plant. It is capable also of generating substances endowed with powers similar to itself. The plan, according to which it acts, displays the most consummate wisdom and foresight, and a knowledge of the properties of matter infinitely beyond what man can boast."

Though the vegetable system is constantly under the observant eye of the philosopher, and subject to his experiments and analysis, yet he has not been able to ascertain how a blade of grass grows. He can discover its general structure; he finds it a vascular, organized body; he will tell us that the

VEGETATION MYSTERIOUS.

He

presence of air, water, and heat, are essential to its vegetation; but still he is obliged to confess that the real operations of the vegetative principle are too mysterious for the utmost stretch of his mind to grasp. But does he therefore deny that there is such a process as vegetation? By no means. fully believes it. But if, perhaps, we converse with this same philosopher on the mysteries of a divine revelation, he will tell us that he utterly rejects them. If we inquire into the reason of this daring impiety, he will reply, that he will believe nothing but what he can comprehend. But where is the consistency of this pretended philosopher? There are two objects which claim a divine origin: there is nothing either in the one or in the other inconsistent with the character of God. Like all other divine operations, they both contain unfathomable mystery and yet, notwithstanding his avowed principle, the one he firmly believes, though he confesses it to be a mystery; and the other he rejects because it is a mystery! The Christian maintains that consistency of character to which the Infidel is a stranger. Confessing his utter incapacity to comprehend the modus of the divine existence, and that it must necessarily be mysterious to finite minds, he justly expects to find in all the works of God something which he cannot comprehend. And so far from rejecting the doctrines of the Sacred Scriptures, on the ground of their being mysterious,